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Web tool · updated

AI subscription vs API calculator

Are you overpaying for ChatGPT Plus, Claude Pro or Google AI Pro? Set how often and how much you chat, and see what the same use would cost through the API, plus the number of messages a day where the plan starts paying off.

  • ChatGPT Plus & Pro
  • Claude Pro & Max
  • Google AI Pro
  • Break-even per day
  • Dated prices

Subscription vs API calculator

Verdict

The API is cheaper by $15.47/month

Break-even at about 88 messages a day with GPT-6.1 Sol. Below that the API costs less; above it the plan does.

ChatGPT Plus$20.00

flat monthly price

API · GPT-6.1 Sol$4.53

0.87M in + 0.28M out tokens

Before you switch

  • The plan includes apps, web search, file uploads, image tools and voice. The API is only the model.
  • With the API you need a chat app that takes your own key, and you pay for every retry.
  • Plans have usage caps; heavy days can hit them. The API has no cap, only the bill.

ChatGPT Plus: $20/month, checked Sep 25, 2026. Billed monthly, no annual option.

Cheaper ways to pay for ChatGPT Plus
Every plan against its matching API model at your usage
PlanMatching API modelPlan / moAPI / moCheaper
GPT-6.1 Sol$20.00$4.53API
GPT-6 Astra$100$22.65API
Claude Sonnet 5.5$20.00$6.47API
Claude Opus 5.5$100$12.95API
Gemini 4 Argon$19.99$4.53API
Gemini 4 Argon$99.99$4.53API

▸ Steps

How to compare a subscription with the API

  1. 1

    Pick the plan

    Choose the subscription you pay for or are considering, such as ChatGPT Plus, Claude Pro or Google AI Pro. The API model it maps to is set for you.

  2. 2

    Describe how you chat

    Set messages per day, how long your prompts and replies are, how many messages a chat runs to, and any documents you paste in.

  3. 3

    Read the break-even

    Compare the monthly API cost with the plan price, and see how many messages a day it takes before the plan is the cheaper way to pay.

▸ Method

How the calculator works

Each message sends your prompt plus everything earlier in the chat, and gets a reply back. For a chat of n messages, the input is n × (your prompt + pasted docs) plus (prompt + reply) × n(n−1)/2 for the history. Output is n replies. That is multiplied out to a month and priced at the model's standard rate, including long-prompt rates where a model has them.

It leaves out prompt caching and batch discounts, which can cut API costs further, and the plan's usage caps, which can make a plan less useful on very heavy days.

Want an exact token count for a real prompt? Paste it into the AI token counter. Staying on a plan? See current offers for ChatGPT Plus, Claude and Google Gemini.

▸ FAQ

Questions

Is ChatGPT Plus cheaper than the API?

It depends on how much you chat. With medium messages (about 60 words in, 350 out) and 6-message chats, the API matches ChatGPT Plus at roughly 88 messages a day on GPT-6.1 Sol. Light users usually pay less on the API; daily heavy users are better off on the plan.

Is ChatGPT Plus worth $20 a month?

As a pure cost question, only if you send more than about 88 medium messages a day; below that the same chats cost less on the API. Plus also covers image generation, voice, file uploads and web search, which the API price does not, so if you use those it can be worth it at lower use.

Is Claude Pro worth it compared with the Claude API?

With the same medium usage, the Claude API costs as much as Claude Pro at about 62 messages a day on Claude Sonnet 5.5. Claude Pro also includes Claude Code and the apps, which the API price does not cover.

Why do long chats cost more on the API?

The API has no memory. Every new message re-sends the whole conversation so far as input tokens, so the tenth message in a chat costs far more than the first. Starting new chats for new topics keeps API costs down.

Where do the prices come from?

Plan prices come from each provider's pricing page and carry the date QuestLoops last checked them. API prices are the standard per-token rates from OpenAI, Anthropic and Google, shared with our AI token counter.

How are words turned into tokens?

English averages about 1.33 tokens per word on OpenAI's tokenizer. Claude 4.7 and newer models count roughly 30% more for the same text, which the calculator applies. Code and other languages use more tokens per word.

What do I lose by switching to the API?

The apps: web search, file uploads, image generation, voice, memory and projects. You also need a chat app that accepts your own API key. If you mostly do plain text chat, that may not matter; if you rely on those features, the plan is the better deal.

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